Biology HESI A2 Practice Exam

Correct Answer: A

Rationale: The correct answer is A: Sucrose. Sucrose is a disaccharide composed of one molecule of glucose and one molecule of fructose. It is formed by a condensation reaction between these two monosaccharides. Fructose (choice B), glucose (choice C), and galactose (choice D) are all monosaccharides, not disaccharides. Therefore, they are incorrect choices for this question.

Correct Answer: C

Rationale: The correct answer is C (12 chromosomes). During mitosis, a cell replicates its chromosomes and divides into two daughter cells, each containing the same number of chromosomes as the parent cell. Since the parent cell has 12 chromosomes, each daughter cell will also have 12 chromosomes after division. Choice A (3 chromosomes) and B (6 chromosomes) are incorrect because they do not account for the full set of chromosomes in the parent cell. Choice D (24 chromosomes) is incorrect as it would only be the total number of chromosomes if each daughter cell received the full set, which is not the case in mitosis.

Correct Answer: C

Rationale: The correct answer is C: Glucose. In photosynthesis, glucose is not a reactant but a product synthesized as a result of the process. Water (A), light energy (B), and carbon dioxide (D) are all reactants in photosynthesis. Water is split into oxygen and hydrogen ions, light energy is absorbed by chlorophyll to initiate the process, and carbon dioxide is converted into glucose through a series of biochemical reactions. Therefore, glucose is the only option that is not a reactant in photosynthesis.

Correct Answer: C

Rationale: The correct answer is C: Commensalism. In this scenario, the cattle benefit from having the insects controlled by the cattle egrets, while the cattle egrets benefit from the insects stirred up by the cattle. The cattle are unaffected by the presence of the egret, making it a one-sided relationship where one species benefits (egrets) while the other is neither harmed nor helped (cattle). This is a classic example of commensalism, where one species benefits while the other remains unaffected. A: Mutualism refers to a relationship where both species benefit, which is not the case here. B: Parasitism involves one species benefiting while the other is harmed, which is not the case in this scenario. D: Competition occurs when two or more species compete for limited resources, which is not the case here as the cattle and cattle egrets are not competing but rather benefiting from each other's presence.

Correct Answer: C

Rationale: The correct answer is C: rod-shaped. Bacillus subtilis is a type of bacteria known for its rod-shaped morphology. This shape is characteristic of this specific bacterium and distinguishes it from other bacterial shapes such as spiral (A), globular (B), and grape-like clusters (D). The rod shape of Bacillus subtilis allows it to efficiently reproduce and adapt to various environments. This morphology also plays a role in its motility and survival strategies. By understanding the distinct rod-shaped morphology of Bacillus subtilis, one can accurately identify and differentiate it from other bacterial species.